On the generalization of the logistic law of growth

This communication presents a discussion of some extensions of the formalism of Verhulst's simple logistics, which may constitute an autonomous growth model of a more general scope.For that purpose, the basis concept of growth diagram or trajectory is called upon, as it affords the graphic representation of the change in the growth variable y, using two relevant kinetic parameters: the instantaneous rate and the instantaneous acceleration. The two possible kinds of trajectories are in relation to the use of absolute (V = dyldt; = dV/dt) or relative (or specific) values (R = (1/y)(dy/dt); _R = dR/dt).In the case of simple logistics, the trajectory (V, ) allows 4 growth phases or states to be distinguished. The diagram (R, _R ) shows that the deceleration of the specific rate is not monotonous.In the case of Richards - Nelder's generalized logistics, the qualitative variation of the growth trajectory depends on the value of the dissymmetry parameter (occurrence of a critical value which determines the number of growth states).Blumberg's model is characterized by an analogous property and, moreover, can account for a non monotonous variation of the specific growth rate.     

军标菌株生活史中各阶段生长发育时间的研究

为了更好地研究军标菌在其应用中的实验周期问题 ,采用插片培养法和载片培养法对军标中 5株实验菌的生活史中各阶段生长发育所需时间进行了研究。结果表明 ,5株菌的各时期生长发育所需时间有所不同。整个生活史最长的 4940min ,如AS 3 .42 5 4。最短的 3 888min ,如AS 3 .3 95 0。孢子萌发阶段所需时间也各不相同 ,最长的需 1 5 2 0min ,如AS 3 .3 885。最短的需 640min ,如AS 3 .3 95 0。这一研究为军标中霉菌试验周期 ,即 2 8d过长而且完全可缩短试验周期的观点 ,提供了有力的证据。     

The morphology of the otoliths of the bagrid catfish,chrysichthys nigrodigitatus (lacepede) and their use in age determination

Two pairs of otoliths, the saccular and sagittae are shown to be well developed in the catfish,Chrysichthys nigrodigitatus. The gross morphology of each pair is provided. Growth markings arranged in a periodic manner are demonstrated. In addition, daily growth marks are shown to be present. The growth markings on the sagittae are interpreted and used in estimating the age and growth of the species.     

以比生长速率时间曲线为基础的生物群体生长数学模型

构建了一个描述限制性环境条件下生物群体生长规律的数学模型。模型中比生长速率(μ)是时间(t)的函数。模型可以很好地拟合多种生物或生物细胞群体生长的延迟期、指数期和稳定期。该模型参数少,模型参数生物学意义明确,计算简单。     

Growth of the Brown Alga <Emphasis Type="Italic">Laminaria japonica</Emphasis> in a Laboratory Environment

The growth of an individual thallus of the brown alga Laminaria japonica was studied in a laboratory environment. It was found that daily accretion of the Laminaria thallus can remain constant for a long time. The blade grew in length at a distance from 0 to 15–25 cm from the stipe-blade border, which makes up 60% of the blade length. In width, the blade grew both in the central and in the lateral parts of the blade, 0 to 7–10 cm from the stipe-blade border, which makes up 30% of the frond length. The transposition of a perforation hole mark from the stipe-blade border toward the blade tip evidenced the formation of new tissue in the growth zone even when the thallus diminished in size due to destruction of the blade tip. Based on the results of this observation, it was concluded that both restraint of accumulation and even reduction of the algal thallus in biomass and size cannot be taken as an indication of algal growth cessation.Original Russian Text Copyright ¢ 2005 by Biologiya Morya, Skriptsova, Leletkin.     

Monthly changes in the gain and loss of growth in weight of children living in Guatemala.

Monthly increments of weight growth for a sample of 246 Guatemala City private school children are analyzed for the presence of a seasonal pattern in rates of growth. Neither a seasonal pattern nor any other periodic rhythm is found. It is observed that a significantly greater number of children aged 5.0 to 6.9 years experience their minimum annual growth rate during the dry season, with up to 60% of them losing or not gaining weight in any one month. Patterns of diet, exercise and disease cannot explain this trend. A possible association between minimum weight growth and maximum growth in height is discussed.     

Pattern of growth in weight of alate and apterous nymphs of the English grain aphid, Sitobion avenae

Daily increase in fresh weight was recorded for apterous and alate nymphs of S. avenae at 20°C. Comparison with a control group indicated that daily disturbance and weighing of nymphs did not affect significantly their growth, developmental time or survival. The increase in fresh weight of apterous and alate virginoparae at 20°C was best described by logistic equations. Alate virginoparae were significantly heavier than apterous virginoparae at birth and throughout most of their nymphal life, but they experienced a weight loss at the final ecdysis. The relative growth rate did not remain constant, but declined during development. The decline is associated with a decline in honeydew production per unit body weight. The implications of an inconstant relative growth rate and the marked loss in weight at the adult moult in alates are discussed.

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Résumé L'enregistrement de l'augmentation quotidienne du poids frais à 20°C des larves ailées et aptères de S. avenae a montré que des perturbations quotidiennes n'affectent pas significativement la croissance, la durée du développement et la survie. Les équations logistiques décrivent plus exactement l'augmentation de poids frais des aptères et des ailés virginipares à 20°C. Les virginipares ailés étaient significativement plus lourds que les virginipares aptères à la naissance et pendant la plus grande partie de la vie larvaire, mais présentaient une perte de poids à la mue finale. Le taux de croissance relative ne restait pas constant, mais diminuait au cours du développement. La diminution était associée à une diminution de la production de miellat par unité de poids du corps. La discussion porte sur les conséquences de la variation de l'augmentation du poids relatif et de la perte marquée de poids à la mue imaginale.

     

Ontogeny of the response to growth hormone-releasing factor

Primary cell cultures were prepared from fetal, neonatal and adult rat pituitaries and evaluated for their ability to secrete growth hormone (GH) in response to growth hormone-releasing factor (GRF). Pituitary cells prepared from fetuses at days 19 and 21 of gestation, neonatal animals at the day of birth (day 0) or the following day (day 1) and peripubertal male rats showed full dose response curves to GRF with maximal GH release when stimulated with 1 X 10(-10) M rat GRF. At this concentration of GRF, the amount of GH released was not different from that elicited by activation of adenylate cyclase with 1 X 10(-5) M forskolin. In contradistinction, a preparation of cells from fetuses at day 18 of gestation did not show the same release of GH when challenged with 1 X 10(-10) M GRF and forskolin (0.057 +/- 0.001, compared to 0.076 +/- 0.003 micrograms/10(5) cells per 4.5 h), although the cells clearly responded to both secretagogues (basal levels of GH, 0.029 +/- 0.002 micrograms/10(5) cells per 4.5 h). While cells prepared from fetuses at day 21 of gestation or from animals after birth released 5-10% of their total cellular GH content, those prepared from 18- and 19-day fetuses released as much as 40% of their total GH suggesting there is a maturation of intracellular GH processing that occurs late in gestation. The results show that, in late pregnancy, the rat fetal pituitary is highly responsive to growth hormone-releasing factor and suggest that this peptide participates in regulating GH levels during the perinatal period.     

Acute Regulation of the Epidermal Growth Factor Receptor in Response to Nerve Growth Factor

PC12 cells possess specific receptors for both nerve growth factor and epidermal growth factor, and by an unknown mechanism, nerve growth factor is able to attenuate the propagation of a mitogenic response to epidermal growth factor. The differentiation response of PC12 cells to nerve growth factor, therefore, predominates over the proliferative response to epidermal growth factor. We have observed that the addition of nerve growth factor to PC12 cells rapidly produces a decrease in surface 125I-epidermal growth factor binding capacity. Unlike previously described nerve growth factor effects on 125I-epidermal growth factor binding capacity, which required several days of nerve growth factor exposure, the decreases we report occur within minutes of nerve growth factor addition: A 50% decrease in 125I-epidermal growth factor binding capacity is evident at 10 min. This rapid nerve growth factor response is concentration dependent; inhibition of 125I-epidermal growth factor binding is detectable at nerve growth factor levels as low as 0.2 ng/ml and is maximal at approximately 50 ng/ml, consistent with known ranges of biological activity. No demonstrable differences in the rate of epidermal growth factor receptor synthesis or degradation were observed in cells acutely exposed to nerve growth factor. Scatchard analysis revealed that acute nerve growth factor treatment decreased the number of both high- and low-affinity 125I-epidermal growth factor binding sites, while the receptor affinity remained unchanged. We have also investigated the involvement of various potential intracellular mediators of nerve growth factor action and of known intracellular modulatory systems of the epidermal growth factor receptor for their capacity to participate in this nerve growth factor activity.     

Light-, nitrogen-, and phosphorus-limited growth of Phaeodactylum tricornutum Bohlin strain TFX-1: Chemical composition,carbon partitioning,and the diel periodicity of physiological processes

Phaeodactylum tricomutum Bohlin (strain TFX-1) was grown under light-, nitrogen-, and phosphorus-limited conditions in continuous or semicontinuous cultures under a 12L-12D light regime. The C, N, and P contents were determined at each steady state, as was the partitioning of cellular organic carbon into protein, lipids, polysaccharides, and metabolic intermediates. All determinations were made at the beginning and again at the end of the light period. The rates of nutrient assimilation and of synthesis of biochemical constituents during the light and dark periods were calculated from the above data, and the periodicities of these processes characterized. The elemental composition of the cells was different under each limitation. In particular, phosphorus limitation severely restricted the ability of the cell to store nitrogen in non-protein forms. Biochemical composition and the diel periodicity of cellular processes also differed between limitations. Nutrient uptake was most strongly periodic under light limitation. Protein synthesis showed increased periodicity under nitrogen limitation, relative to the other limitations, while the periodicity of lipid synthesis was reduced under phosphate limitation. Polysaccharide was synthesized at high rates during the light period and consumed in the dark under all limitations.     

8个引进苜蓿品种的生长特性比较研究

通过对国外引进的 8个苜蓿品种在同一环境条件下的生育期、生物量及其相关性状的动态变化特征进行比较研究 ,结果表明 ,8个苜蓿品种的返青期、分枝期有较大差异 ,而现蕾期、开花期差异较小 .8个苜蓿品种的生长性状动态变化为 :株高和茎粗在品种间差异很小 ,株高呈直线增长趋势 ,而茎粗的增长非常缓慢 ;8个苜蓿品种的叶面积在不同生育期的动态变化为 :返青期品种间无差异 ,从分枝期到开花期品种间差异很明显 ;分枝数在整个生育期品种间差异较大 ;生物量与其相关性状叶面积、茎粗和分枝数呈极显著正相关 ,而与株高呈不显著正相关     

Bioactive compounds from the edible mushroom Cortinarius caperatus

Six compounds, 5-(1-hydroxyethyl)dihydrofuran-2(3H)-one (1), 4-ethoxy-4-oxobutanoic acid (2), 4-ketononanoic acid (3), methyl(2-acetylaminoethyl)sulfoxide (4), methyl benzoate (5) and p-hydroxybenzoic acid (6) were isolated from the fruiting bodies of Cortinarius caperatus. Compounds 1, 3, 5, and 6 inhibited growth of Flammulina velutipes mycelia. Compounds 2, 3, 5, and 6 exhibited growth regulatory activities toward rice seedlings, while compounds 3, 5, and 6 regulated the growth of lettuce. Compound 4 was first isolated from a natural source. In addition, the activity of compound 6 against rice was compared with those of its analogs.     

The role of stress in the growth of a multicell spheroid

Rather recent experimental results demonstrate the non–negligible role of mechanical stress in the growth of a multicell spheroid. In this paper we discuss a theoretical framework for volumetric growth suitable for modeling the growth of soft tissues exhibiting the properties of a solid. After a proper kinematic decomposition, balance equations for mass, momentum and energy are discussed together with constitutive relationships. The mathematical model is then applied to avascular tumor growth. We show by numerical simulation that, under assumption of spherical symmetry, the mathematical model is able to reproduce the experimental data with a satisfying qualitative agreement.     

Hrs regulates the endocytic sorting of the fibroblast growth factor receptor 2b

The keratinocyte growth factor receptor or fibroblast growth factor receptor 2b (KGFR/FGFR2b) is activated by the specific interaction with the keratinocyte growth factor (KGF/FGF7), which targets the receptor to the degradative pathway, and the fibroblast growth factor 10 (FGF10/KGF2), which drives the receptor to the juxtanuclear recycling route. Hrs plays a key role in the regulation of the endocytic degradative transport of ubiquitinated receptor tyrosine kinases, but the direct involvement of this protein in the regulation of FGFR endocytosis has not been investigated yet. We investigated here the possible role of Hrs in the alternative endocytic pathways of KGFR. Quantitative immunofluorescence microscopy and biochemical analysis showed that both overexpression and siRNA interference of Hrs inhibit the KGF-triggered KGFR degradation, blocking receptor transport to lysosomes and causing its rapid reapparance at the plasma membrane. In contrast, the FGF10-induced KGFR targeting to the recycling compartment is not affected by Hrs overexpression or depletion. Coimmunoprecipitation approaches indicated that Hrs is recruited to KGFR only after KGF treatment, although it is not tyrosine phosphorylated by the ligand. In conclusion, Hrs regulates the KGFR degradative pathway, but not its juxtanuclear recycling transport. In addition, the results suggest that Hrs recruitment to the receptor, but not its ligand-induced phosphorylation, could be required for its function.     

Importance of the caryopsis in root growth and georeaction

Geocurvature of horizontally placed apical segments of maize (cv. INRA 258), the lateral curvature of half-decapitated segments in vertical position, and the curvatures of intact primary roots (horizontal or vertical) still attached to their caryopses were analysed in white light. The results may be explained in terms of the growth properties of certain endogenous regulators. The caryopsis could be the source of some precursors of growth inhibiting substances produced or released in the cap cells and also of growth activators. The relative effects of these factors – acting in the elongating zone of growing roots – clearly depend on the orientation of the caryopsis.     

Serum insulin-like growth factor 1 concentrations in the developing rhesus monkey.

We studied the developmental pattern of serum IGF-1 concentrations in the rhesus monkey in cross-sectional and longitudinal manners. Values were lower in infants with a significant rise at the onset of puberty. Females values were lower than males except for pregnant females. There was a correlation of IGF-1 values with body weight in the males. Longitudinal study of six animals proved this age dependence of IGF-1 values. The rhesus monkey has a pattern of serum IGF-1 concentrations similar to that of the human being.     

Protein synthesis during the transition from the resting to the growing state in suspension cultures of Paul's Scarlet rose cells

Cells derived from Paul's Scarlet rose ( Rosa sp. ) were grown in the chemically defined medium of Nesius. When a stationary phase culture was diluted with fresh medium, growth was initiated after a pronounced lag period. DNA replication, as revealed by thymidine labeling and autoradiography, did not begin until 36 h, and mitotic figures were not observed until 48 h after dilution. A 10–15 fold increase in the rate of protein synthesis occurred during the lag period. This was brought about by a 3.5 fold increase in the amount of ribosomal RNA per cell, plus a doubling of both the percentage of ribosomes that are present as polyribosomes and the average number of ribosomes per polyribosome. The spectrum of polypeptides synthesized by these cells during the lag and early log periods of growth was examined. Polyribosomes were extracted from the cells at intervals preceding and accompanying the initiation of proliferative growth. The polyribosomes were translated in a wheat germ cell-free protein synthesizing system and the ³⁵S-methionine-labeled translation products were separated on polyacrylamide slab gels and by 2-dimensional gel electrophoresis. Comparatively few differences were observed between stationary phase, lag phase and log phase cells in terms of the spectrum of polypeptides synthesized in vitro. However, these various phases of the growth cycle could be characterized by a relatively high rate of synthesis of a few specific polypeptides. That is, while most proteins are synthesized throughout the growth cycle and even in non-growing cells at approximately the same relative rates, there are a few variable proteins whose synthesis marks a particular phase of the growth cycle.     

Developmental changes in the facial soft tissues

Short-base stereophotogrammetry was used to study differential growth and development of the soft tissues of the face. Thirteen facial parameters were measured at ages 9, 11, 13, 15, and 16 years on 170 facial contour maps selected from a mixed longitudinal study of 26 boys and 26 girls. Each parameter was measured three-dimensionally, and its developmental progress at the earlier stages was expressed as a percentage of its value at 16 years of age. Standing height development was assessed in the same way. Three parameters that measured soft tissues surrounding the eyes grew little but were very advanced in their development, following a "neural" pattern. The remaining facial parameters grew more but were less advanced, and standing height was least advanced. There appeared to be three separate patterns of development, "neural," "facial," and "skeletal." Girls were, in general, smaller than boys, but their development was more advanced when measured as a percentage of size at 16 years compared with boys.     

The growth of children in relation to the timing of obesity development

Objective: To examine whether there is an association between the timing of the development of obesity and children's growth. Research Methods and Procedures: This study investigated 141 prepubertal obese children (76 girls) and 72 healthy non‐obese children (39 girls). The target height standard deviation score (SDS), the percentage weight for height, and the height SDS (H‐SDS) at presentation and at the age of 2 years were calculated. Patients were classified, according to whether obesity developed before or after the age of 3 years, as presenting with early‐onset or late‐onset obesity, respectively. Results: Mean age (±SD) at presentation was 9.4 (2.1) years. At the age of 2 years, the H‐SDS of the children with early‐onset obesity was 1.3 (1.0) vs. 0.9 (1.3) for the late‐onset obese (p > 0.5) and 0.4 (1.0) for controls (p < 0.001), and the children with late‐onset obesity were also significantly taller than controls (p < 0.005). At presentation, children with early‐onset obesity were significantly taller than children with late‐onset obesity [1.1 (0.8) vs. 0.6 (1.0); p < 0.001] and controls [0.2 (0.8); p < 0.001]. There was no increase in H‐SDS after the age of 2 years in the late‐onset obese children (p > 0.05). H‐SDS values were below average in 21% of the children with late‐onset obesity and in only 4% of the children with early‐onset obesity. Discussion: These findings indicate that late development of obesity is not associated with increased stature in prepubertal children; however, it may be preceded by growth acceleration in the early years of life. Growth acceleration in early life may be a predictor for future obesity.